1. Field of the Invention
This invention relates to a solidification technique for solidifying liquid films formed on the upper surfaces of various substrates such as semiconductor substrates, glass substrates for photo mask, glass substrates for liquid crystal display, glass substrates for plasma display, substrates for FED (Field Emission Display), substrates for optical disc, substrates for magnetic disc and substrates for opto-magnetic disc (hereinafter, merely written as “substrates”) and a substrate processing method and a substrate processing apparatus for cleaning the upper surface of a substrate using the solidification technique.
2. Description of the Related Art
A manufacturing process of an electronic component such as a semiconductor device or a liquid crystal display device includes a step of forming a fine pattern by repeatedly applying processes such as film formation on a surface of a substrate and etching. Here, the substrate surface needs to be kept in a clean state to satisfactorily perform fine processing and a cleaning process is performed on the substrate surface if necessary. For example, in an apparatus described in JP2008-71875A, a liquid such as DIW (DeIonized Water: hereinafter, written as “DIW”) is supplied to a substrate surface and, after the liquid is frozen, the frozen liquid is thawed and removed with a rinse liquid, whereby the substrate surface is cleaned.
Specifically, in the apparatus described in JP2008-71875A, the following steps are performed. First, a substrate surface is arranged in a horizontal posture with a surface faced upward and a DIW liquid film is formed on the entire surface of the substrate by supplying DIW to the surface (upper surface) of this substrate. Subsequently, the supply of the DIW is stopped and nitrogen gas having a low temperature is blown toward the surface of the substrate to freeze the DIW liquid film. In this way, the DIW having entered between contaminants such as particles and the surface of the substrate becomes ice and expands, whereby the contaminants such as particles are moved away from the substrate by a minute distance. Further, the DIW expands also in a direction parallel to the surface of the substrate, thereby releasing particles and the like fixed to the substrate. As a result, adhesion between the surface of the substrate and the contaminants such as particles is reduced and the contaminants such as particles are eliminated from the surface of the substrate. Thereafter, by thawing and removing the ice present on the surface of the substrate with the DIW as the rinse liquid, the contaminants such as particles can be efficiently removed from the surface of the substrate.